1. Field of the Invention
The invention relates to an optical module, and more particularly to a backlight module.
2. Description of Related Art
With rapid progress in display techniques, a flat panel display has become mainstream among various displays and replaced a cathode ray tube (CRT). Among various flat panel displays, a liquid crystal display (LCD) has been deeply favored by the consumers for usage. Generally, the LCD is mainly formed by a backlight module and a liquid crystal display. Since the LCD does not emit light by itself, it is required that the backlight module provides a planar light source required for displaying.
Generally, the conventional backlight module is categorized into a direct-type backlight module and a side-type backlight module. For example, the side-type backlight module is usually utilized a light guiding plate to guide light emitted from a light source disposed beside the light guiding plate, so as to provide the planar light source required for a display panel.
For the side-type backlight module which utilizes light emitting diode as the light source, a plurality of light emitting diodes are disposed beside a light incident surface of the light guiding plate. Because the light emitting diode has a specific range of light emitting angles, a phenomenon known as “hot spot” is prone to occur in an area near to the light incident surface of the light guiding plate. The hot spot phenomenon is a problem to cause overall uniformity of the planar light source being lower due to insufficient mixing light distance or uneven mixing light. As a result, it is difficult to improve the overall optical quality of the liquid crystal display panel.
Taiwan Patent No. I283781 discloses a structural design of a light guiding plate, in which steps are capable of destructing a light traveling path formed at a bottom surface of the light guiding plate. P.R.C. Patent No. 101680635 discloses a structural design of a wedge shape light guiding plate, in which a light source and a reflector are respectively disposed at two opposite sides of the wedge shape light guiding plate, and a thickness of the wedge shape light guiding plate at a side near the light source is relatively lower and the thickness of the wedge shape light guiding plate at a side near the reflector is relatively higher. Taiwan Patent No. M247857 discloses a structural design of a wedge shape light guiding plate, in which a light beam is lead to the outside of the light guiding plate by scattering patterns located at bottom of the wedge shape light guiding plate guides. P.R.C. Patent No. 102483522 discloses a light source and a reflector respectively disposed at two opposite sides of the light guiding plate, wherein the reflector includes a curvature. Taiwan Patent No. I235807 discloses a structural design of a light guiding plate, wherein an inclined reflecting surface is provided at an end surface of the light guiding plate opposite to a light source, and light reflected by the reflecting surface is immediately emitted from the light guiding plate. Taiwan Patent No. 534325 discloses a light guiding plate having light sources disposed at two opposite sides, and a reflecting surface at a bottom surface of the light guiding plate is substantially an inclined surface of an inverted V shape. U. S. Patent Publication No. 20120314145 discloses a wedge light guiding plate having a bottom surface coated with a reflecting layer and a wrinkled end surface, wherein the wrinkled end surface is opposite to a light incident surface and the wrinkled end surface is also coated with a reflecting layer. Taiwan Patent No. 201020596 discloses a light guiding plate includes prism microstructures disposed on a top surface and a bottom surface, and an extending direction of a normal of a light incident surface is substantially parallel to an extending direction of the prism microstructures of a light emitting surface.